The invention pertains to an apparatus for comminuting solid waste materials such as sheet material. More particularly, this invention relates to a comminuting apparatus having pneumatic conveyors and pneumatic recirculation systems for comminuting solid waste material such as foamed plastic sheet material.
The manufacture and forming of many products from plastic produces significant amounts of plastic waste material. Applicant has previously invented several unique apparatus for comminuting severable waste material, particularly plastic sheet material, into small, rather uniform particles or pieces that can be readily recycled or disposed of in an environmentally acceptable manner. Several generations of product line have been sold by Irwin Research and Development, Inc., under the product name xe2x80x9cChesawxe2x80x9d and have gained commercial success. One such prior invention is the subject of the Irwin, et al., U.S. Pat. No. 4,687,144 granted Aug. 18, 1987. Other such prior inventions are the subject of U.S. Pat. Nos. 5,836,527; 5,860,607; and 5,893,523. However, additional improvements are needed, especially due to the use of relatively light, foamed plastic sheet material and further due to increases in operating speed that have been realized with new motors. As a consequence, there has been found to be an increased tendency for subdivided particles to accumulate within a recycle manifold so as to collect and clog such recycle manifold, which can significantly reduce operating speeds and throughput.
As an example of prior inventions, U.S. Pat. No. 5,836,527 was an improvement over the invention of U.S. Pat. No. 4,687,144. More particularly, an improved comminuting apparatus is provided which can significantly increase the amount of comminuted material produced in a given amount of time. Such device is relatively less expensive to manufacture, is quieter to operate, and provides an ability to comminute a wider variety of solid waste materials. More particularly, the solid waste comminuting apparatus carries material that is severed in the device via an airstream through a fan. Subdivided pieces of material are directed via the fan to a separator screen which is mounted within a centrifugal housing. The airstream draws a relative vacuum beneath the separator screen that carries small pieces through the separator screen into an outer volute chamber for discharge from the apparatus. Large pieces which are not capable of passing through the separator screen are recycled through a recycle outlet and a recycle conduit back to scissor rolls of the device for further size reduction. However, the complexity of the apparatus and the number of parts needed to construct the apparatus increased over the device of U.S. Pat. No. 4,687,144, which has proven undesirable for certain applications.
Another example of a prior invention is disclosed in U.S. patent application Ser. No. 09/419,822, filed Oct. 15, 1999, entitled xe2x80x9cDownstream Pneumatic Recirculation Comminuting Apparatusxe2x80x9d, naming Jere F. Irwin as inventor. Such U.S. patent application Ser. No. 09/419,822 is incorporated herein by reference. Such patent application is directed to a downstream recirculation comminuting apparatus that uses improved pneumatic conveyor and material extraction features. More particularly, a pneumatic conveyor communicates with a shear outtake manifold to generate an air stream through a shear outtake manifold of sufficient velocity to entrain and remove subdivided pieces from the shear outtake manifold that might otherwise tend to collect and clog the shear outtake manifold. However, the utilization of such machine when subdividing certain types of material still needs further improvement. For example, the comminuting of relatively lightweight, foamed plastic sheet material tends to clog in the recycle manifold. Accordingly, such improvements are overcome by the present invention.
The present invention provides a vastly improved comminuting apparatus that is not only able to process significantly greater amounts of material in a given time, it is also better able to recirculate and sort severed solid waste material utilizing an apparatus that is less likely to clog from subdivided pieces accumulating within the recycle manifold. The improved comminuting apparatus of the present invention is formed with a relatively simple construction having a minimum number of moving parts, proves more reliable and less costly to manufacture than alternative devices, is easier to maintain and repair, and is more efficient to operate. It is also better able to sever a wider variety of different types of materials, particularly for lightweight foamed plastic materials, over a broader range of line speeds with increased levels of throughput of a web of material being received from a processing machine. Accordingly, the present invention provides an apparatus that is able to better move subdivided solid waste material through the comminuting apparatus without clogging in a relatively efficient and cost-effective manner, while also being able to handle a wide variety of severable materials at higher operating speeds and material feed rates.
The present invention provides a vastly improved comminuting apparatus that is also better able to receive sheets of solid waste material through the primary in-feed slot of an entry chute for comminuting between scissor rolls, particularly in an apparatus having a relatively simple construction with relatively few moving parts, which is relatively less costly to manufacture, maintain and repair, and is more reliable.
A self-feeding comminuting apparatus is provided having improved pneumatic entry air and overflow air recirculation systems. According to one improvement, a pair of overlapping scissor rolls cooperate to feed waste material between the pair of scissor rolls to a recycle manifold section. The recycle manifold section delivers subdivided pieces to one of the scissor rolls to recycle the subdivided pieces for sorting and/or recirculation between the pair of scissor rolls for further subdividing. The overflow air recirculation system encourages movement of subdivided material collecting within the recycle manifold into a recirculation cavity for further subdividing between the scissor rolls. According to another feature, the entry air recirculation system communicates with the entry chute to deliver a cushion of air between a sheet of material being received within the entry chute for severing between a pair of scissor rolls. Such stream of air enhances the delivery of the sheet of material into the entry chute by minimizing frictional contact therebetween so as to float the sheet of material for more stable and efficient delivery into and between a pair of scissor rolls for comminuting therebetween.
According to one aspect of the invention, a comminuting apparatus is provided which includes a frame, at least one drive motor, a set of overlapping scissor rolls and a recycle manifold. The frame has an enclosure with an entrance opening for receiving waste material. At least one drive motor is carried by the frame. The set of overlapping scissor rolls includes a first scissor roll and a second scissor roll carried within the enclosure for co-rotation and driven by the at least one drive motor, configured to draw material from beneath for delivery between the overlapping scissor rolls to subdivide the material. The recycle manifold is provided above and downstream of the scissor rolls and is configured to receive the subdivided material from between the overlapping scissor rolls. The pneumatic conveyor comprises a source of air and a pneumatic duct communicates with the recycle manifold, the pneumatic duct is configured to deliver an air stream from the source of air into the recycle manifold to entrain subdivided pieces and move the subdivided pieces from the recycle manifold for further conveying and subdividing within the comminuting apparatus.
According to another aspect of the invention, an invention is provided for a comminuting apparatus having intermeshing cutting blades carried by a frame within an enclosure and a recycling manifold provided above the blades for collecting material subdivided by the blades and an overflow fence along the recycling manifold over which subdivided material cascades for delivery back into the blades. The invention includes a pneumatic conveyor, a recirculation air pipe, and an air delivery duct. The pneumatic conveyor generates a source of air and the recirculation air pipe communicates with the pneumatic conveyor at a first end; and an air delivery duct communicates with the pneumatic conveyor via the recirculation air pipe at a second end for delivering a source of air into the recycle manifold to impinge upon subdivided material that collects within the recycle manifold behind and above the overflow fence so as to move the recycled material over the overflow fence for further comminuting.
According to yet another aspect of the invention, an air recirculation system is provided for a comminuting apparatus having a recycle manifold with an overflow fence where subdivided pieces of material cascade from the recycling manifold over the overflow fence for further comminuting via intermeshing cutting blades. The invention includes a source of air, an overflow air recirculation pipe, and a recycling air delivery duct. The overflow air recirculation pipe communicates with the source of air. The recycling air delivery duct communicates with the pneumatic conveyor via the overflow air recirculation pipe and is configured to impinge the source of air upon subdivided material collecting in and above the recycle manifold to encourage moving the subdivided material over the overflow fence for further comminuting between the intermeshing cutting blades.
According to even another aspect of the invention, a comminuting apparatus which includes a frame, an enclosure carried by the frame, at least two intermeshing scissor rolls, and a pneumatic conveyor. The enclosure carried by the frame has a material receiving duct for receiving a sheet of material. The at least two intermeshing scissor rolls are carried within the enclosure and are configured to subdivide the sheet of material. The pneumatic conveyor for a sheet of material entering the enclosure via the material receiving duct includes a source of air and an entrance air duct provided adjacent the entrance and within the enclosure, and is configured to deliver a stream of air between the sheet of material and an inner wall of the enclosure within the material receiving duct.